New enigma in physics: Dark Energy

Kyshalee Vázquez

Common beliefs concerning the universe are that it is stationary and mainly composed of everything we can perceive with our senses. Actually, when we think about the universe what comes to mind may be stars, planets, galaxies, perhaps black holes and nebulae. However the National Aeronautics and Space Administration states that these celestial bodies only compose less than five percent of the universe, a miniscule portion of such a grand cosmos. Then, what is the remaining portion of the universe made off? And if the universe isn’t stationary, what is causing its motion?

After the Big Bang the universe started to expand, and all the matter was close enough to be pulled together by gravitational forces to form the universe we study today. Astronomers knew the universe was still expanding from the energy of the Big Bang, but it was believed that this expansion was decelerating. This deceleration was attributed to the fact that the universe had enough mass that would pull on each other by gravitational forces, and therefore slow down the process of expansion. However the rate of this deceleration was unknown and consequently two groups of astronomers searched for answers. 

The idea was to find Type Ia supernovae because they reach the same luminosity when they undergo a thermal explosion. By determining the brightness and measuring the redshift it is possible to know the distance of the supernova and how long ago they occurred. Of course this process took a few years because Type Ia supernovae are hard to come by, for their brightness only lasts a few weeks. With the information gathered after this long research process it was evident that the stars were farther away than they should be, if the universe were slowing down. These two groups of astronomers were confused since this information indicates that the expansion of the universe must be accelerating and not decelerating.

As it is usual in science, another question emerged. Why is the expansion of the universe speeding up if it has enough mass to slow it down? A new factor had to be added to this quest that was not considered by these astronomers at first, but it is believed that it was considered by Albert Einstein when he introduced the cosmological constant in is general relativity theory.  Astronomers thought that this new factor, called dark energy, must be a kind of repulsive force that keeps separating the galaxies farther away expanding the universe. 

Although dark energy keeps separating these immense groups of celestial bodies from each other, we shouldn’t worry about it separating Earth from the Sun, because there is yet another presence that like dark energy we cannot perceive with our senses, called dark matter. Dark matter is held responsible for the formation of galaxies, because there is so much dark matter around the celestial bodies creating a gravitational attraction additional to the gravitational pull they already have as masses of normal mater. It is not likely that dark energy will separate the planets or stars in a galaxy itself due to this dark matter. Both dark energy and dark matter are relatively new to our knowledge and very little is known of them.

Finally after this series of discoveries, scientists have concluded that dark energy and dark matter were created in the Big Bang along with normal matter. Because the universe was smaller, all the matter was closer and the force of gravity was greater than dark energy, so the expansion of the universe was slower. As the universe kept slowly expanding dark matter and gravity formed the galaxies, continuously segregating them farther apart. When dark energy overwhelmed the gravitational force, due to the growing distance, the universe started accelerating in its expansion.

Illustration shows the changes in the rates of expansion since the universe’s birth.

Bibliography

Netting, Ruth. "Dark Energy, Dark Matter." NASA Science Astrophysics.    Web. 15 April 2011.

Smale, Alan. "Dark Energy." Imagine the Universe. 29 October 2009.     Web. 15 April 2011.

Villard, Ray and Riess, Adam. "Refined Hubble Constant Narrows Possible Explanations for Dark Energy." HubbleSite. 7 May 2009. Web. 15 April 2011.

Earthquakes: “A real threat that lurks in our future”

Luis M. Rolón Luna

Recently we may have seen or heard the word earthquake by the media and witnessed its powerful capabilities here on the island and throughout the world. Places like Haiti, Japan, Chile, etc. have lived the devastating power and energy an earthquake possesses. A quake is a shock of the land that takes place due to the shock of the tectonic plates and to the liberation of energy in the course of an abrupt reorganization of materials of the terrestrial crust when surpassing the state of mechanical balance. Most important and frequent they take place when accumulated elastic potential energy in the gradual deformation of contiguous rocks is freed to the plane of an active fault, but also can happen by other causes, for example around volcanic processes, or slope movements.

How are trembles produced? They are vibrations of the land caused by an abrupt liberation of energy coming from the edges of tectonic plates. The tectonic plates hit to each other and produce liberation of energy as a result of the efforts that they were supporting. The point in which the earthquake in the surface is detected is the epicenter and the point where the earthquake takes place is the hypocenter. In the hypocenter, the waves disperse towards all directions. First that arrives are the waves P (primary), followed of waves S (secondary). They are different from others in the speed of propagation and in the possibility of crossing surfaces you eliminate, like the external nucleus. Primary P waves are those that are detected first in the seismograph. Also they are waves L, the superficial ones, these they are in surface and they are most destructive, they are also but the slow ones and they are those that cause the damages.

How do quakes affect a building? Most of the earthquakes are the result of a fast movement throughout the plane of faults in the terrestrial crust. This sudden movement of the fault publishes a great amount of energy that travels through the Earth as a seismic waveform.  The seismic waves travel great distances before losing most of their energy. At some time after their generation, these seismic waves will arrive at the Earth surface, and to put it in movement. When this movement of the ground happens under a building and if it is strong enough, the creation of movement commences, beginning with the construction of the foundation, and transfers the movement through rest of the building in a very complex form. When the content of frequency of the movement of the ground is centered around the natural frequency of the building, it is said that the building and the movement of the ground are in resonance with each other. The resonance tends to increase or to amplify the answer of the building. Due to this, the buildings suffer the greater damages by the movement of the ground to a frequency near or equal to their natural frequency.

This is why we must create a seismic conscience in Puerto Rico because we live in a highly active island where earthquakes of different magnitudes occur every day. I greatly recommend that we seek education in what to do before, during and after a quake. This way we can be prepared if the situation presents itself and possibly help others. You can also go to this website www.ciapr.org which is the cybernetic page of the School of Engineers and Surveyors to find orientation and the seismic plan for Puerto Rico. 

References:

1. es.wikipedia.org/wiki/Terremoto. Web. April 22, 2011.

2. http://www.angelfire.com/ri/chterymercalli/. Web. April 22, 2011.

“Beam me up, Scotty”

Jorge Gabriel Concepcion Sanchez

The impossible is that which is considered to be unfeasible or unattainable. We cannot flap our arms and fly, we can’t hold our breath for hours underwater and we cannot see in the dark. Even though these feats are considered impossible to an ordinary human being, through the use of science and technology we human have conquered the skies, journeyed to the watery depths of the ocean and peered into the darkness of the night without the help of light (visible light to be exact). We have seen that as time goes on and technology becomes more and more advanced, science is able to blur the line between the impossible and the possible, turning science fiction into science fact. Dr. Michio Kaku, theoretical physicist and Co-founder of Grand Unified String Field Theory, uses his book “Physics of the Impossible” to demonstrate the underlying physics behind many of the “impossibilities” that today’s scientists toil over so that we may have a better understanding of which are realistically within the reach of our civilization. 

From force fields to parallel universes and perpetual motion machines, Kaku divides the impossibilities that are throughout his book into three categories: Class I, II and III impossibilities. The first refers to “technologies that are impossible today but that do not violate the known laws of physics” and that might become possible in this century or the next. The second concerns those technologies that “sit at the very edge of our understanding of the physical world” and that might be possible in a thousand to a million years. Lastly, Class III impossibilities apply to technologies that “violate the known laws of physics” and that if possible, “would represent a fundamental shift in our understanding of physics.” Intrigued? I know I was. Such things had always caught my attention but I would dismiss them as just that, interesting queries that are ultimately meaningless because of their improbability. It was ignorant to do so, however. Even though Kaku makes the physics behind the impossibilities easy to understand, Class II and III impossibilities are very abstract and my limited knowledge in theoretical physics prohibits me in properly explaining them. As a result, I have chosen to explain the Class I impossibility that intrigued me the most: teleportation.

Teleportation is the capacity to instantly move objects from one place to another. Throughout this semester, we have journeyed through the world of Newtonian physics as objects move because they push and pull on each other. If an object wants to go somewhere, a force has to be exerted in order to move said object to the desired location. Makes sense, right? Well, there’s this thing called Quantum Theory and it doesn’t care much for your common sense. In Quantum Theory, particles like electrons can exhibit wavelike behavior as described by Erwin Schrödinger’s famous wave equation. It may sound weird but electrons can be described as  waves of probability which “tell you only the chance of finding a particular electron at any place and any time.” This probability pertaining to electrons is known as the uncertainty principle which states that “you cannot know both the exact velocity and the position of an electron at the same time.”  Therefore, in the strange world of the Quantum, it makes perfect sense for an electron to be at more than once place at a time and objects are described as the sum of all their possible states since there is no way to know for sure where its electrons are located. This might seem counter-intuitive since the physical world is full of objects that don’t spontaneously disappear and reappear such as our bodies. The human body however, contains trillions upon trillions of electrons and all the quantum events taking place inside our body even out over time giving it the appearance of being solid. Interestingly, if we were to calculate the probability of our body disappearing and reappearing in the next room, we find that we would have to wait “longer than the lifetime of the universe” to witness such a quantum event. This type of event is impossible under Newtonian physics yet is possible in Quantum theory, albeit the probability for it taking place is unimaginably small. 

Einstein didn’t like probability and chance being introduced into the heart of physics once saying, “For my part, at least, I am convinced that [God] doesn’t throw dice.” He and two of his colleagues even performed an experiment in an effort to disprove Quantum Theory based on the idea of quantum entanglement. This is the concept that “ particles vibrating in coherence have some kind of deep connection linking them together.” This means that if two electrons are coherent, meaning they are vibrating at the same frequency, then what happens to one will affect the other regardless of the distance between the two since “there is still an invisible Schrödinger wave connecting both of them”. Not surprisingly, Einstein was unable to disprove Quantum Theory through quantum entanglement and ironically, it is this same concept that is the basis for teleportation.

Quantum teleportation is weird in the sense that an object doesn’t magically appear from one place to the other, rather its information is the one being “teleported”.  To illustrate this, Kaku uses the example of three atoms A, B and C. Suppose we want to transfer the information from atom A to C; also suppose that B and C are coherent. If atom A comes into contact with atom B and becomes coherent, then A’s information is passed to B but since atom B was already entangled with C, then A’s information ultimately ends up in atom C. Strangely enough, if an object were to be teleported, it technically has to die before its information gets transferred to elsewhere creating the exact same object with the same information. It may sound weird but scientists have already been successful in teleporting particles in this manner. One of the most astounding achievements being the entanglement of a light beam with a gas of cesium atoms and teleporting this gas for about a half yard!

Teleportation involving entanglement might not be the as “science-fictiony” as one may had hoped but a way to teleport that is truer to the Star Trek tradition has already been discovered and therefore is called “classical teleportation”. It involves the use of a “Bose Einstein Condensate” or a BEC, one of the coldest substances in the universe. Some of the coldest temperatures in nature can be found in outer space ranging around 3 K above absolute zero (this is due to the residual heat from the Big Bang). A BEC however is “a millionth to a billionth of a degree above absolute zero”, a temperature only producible in a laboratory. BECs are important because at so low a temperature, atoms are at such a low state of energy that they vibrate in unison and therefore become coherent. Essentially, a BEC can be seen, as Kaku comically puts it, as “one gigantic super atom” since the wave functions of the atoms imbricate over one another. The first step in this method of teleportation involves shooting a beam of matter at a BEC where both consist of the same type of atom. As the beam comes in contact with the BEC, the beam’s atoms tumble down to the lowest possible energy state releasing energy in the form of light. Curiously enough, this light carries all the quantum information of the original matter beam so if then the light beam comes into contact with another BEC, a new matter beam identical to the original one is created.

Quantum teleportation is a technology that is deeply intertwined with that of quantum computers which are a new breed of computers that use the concept of quantum entanglement to make calculations. The reason today’s computers are so advanced is because their progress is based on the shrinkage of their components. Their components however cannot shrink beyond a certain threshold because then the uncertainty principle kicks in. Quantum computers are then the most likely candidates to replace their silicon based brethren in the near future. Besides all of the progress that has been made in this field, we are far away from having a personal quantum computer and teleporting ourselves to the mall. The most daunting obstacle is maintaining coherence between a large number of particles since the tiniest vibration is capable of causing decoherence. Quantum computers would require billions of constantly coherent particles in order to compete with today’s computers let alone how much it would take to teleport macroscopic objects such as a human being. Even though there are technical difficulties regarding teleportation, it is exciting to know that it doesn’t violate the laws of physics in any shape or form.

Einstein once said, “If at first an idea does not sound absurd, then there is no hope for it.” Making the absurd possible lies at the very pinnacle of scientific progress and it’s this absurdity which gives our civilization the potential for progress. Teleportation is just the tip of this magnificent iceberg and other even more exciting technologies might be hidden beneath the waves. Rightfully so, our future as a species may lie in the absurdity of such technologies.

Reference:

Kaku,  Michio.  Physics of the Impossible.  1st ed.  New York, NY:  Anchor Books,  2009.

Roller Coaster Physics: Safe or Reckless?

Arnaldo López Rivera

The thrill and the excitement of riding roller coasters has been a goal of mine since the first time I rode one. Always searching and keeping my eyes opened to find the next biggest, fastest and most wild roller coaster to ride next. At times I often wondered. What little tweaks make the roller coaster go faster? How did the engineers manage to keep the cars from falling while doing loops? And the short and simple answer is through basic concepts in physics!

These physic concepts are present in various parts of a roller coaster ride, for example free falling when the coaster goes over a hill, or the change in G forces felt while the ride is in motion, or the inversions felt while going on a loop. The most basic of physics involved in a roller coaster ride is the kinetic and potential energy. In kinetic energy the faster the coaster moves, the more kinetic energy it has.    Potential energy can be thought of as stored energy. Consider when you lift a heavy object. To do this, you exert energy. This energy becomes available as potential energy, which can then become kinetic energy when you drop the object. Similarly, the lift motor of a roller coaster exerts energy to lift the ride to the top of the lift hill, energy that will eventually become kinetic energy when the coaster drops. Lifting the train higher gives it more potential energy. This potential energy is converted to kinetic energy when the train drops. The further it drops, the more potential energy that gets converted to kinetic energy. In other words, the coaster picks up speed as it falls. The G forces are measured in terms of what you feel when you are sitting still in the earth's gravitational field. When in that state, you are in a 1-G environment. While riding a roller coaster 1 G represents the force the rider experiences while sitting stationary in the earth's gravitational field. As the acceleration on the rider changes, the G forces will change as well.

The most difficult aspect to understand in coaster physics is the friction present during the ride. Without taking friction into consideration the acceleration and the sum of the kinetic and potential energy in the ride would remain constant. Taking friction into account, this sum will continually decrease throughout the ride. So later in the ride, the train can't climb as high as it could in the beginning. To climb a high hill may require more energy than the coaster has left. Furthermore, at the bottom of hills, the train will tend to go slower at the end of the ride than it did at the beginning, because to go fast also means having a lot of energy. A well-designed coaster can still exert more extreme forces at the end of the ride than at the beginning for instance, by making the turns tighter.

These are some of the general physic concepts involved in a roller coaster ride, however there is still the question of safety to be answered. Are roller coasters safe? For the most part roller coasters are very safe; engineers design the ride taking into consideration that the rider does nothing unusual. If you stand up in a sit-down coaster, the calculations will no longer apply.

The Physics behind Baseball

Edwin Herrera Montalvo

Baseball is considered America’s pastime since the 1960’s. Baseball is an important part of my life since my grandpa and father were baseball players. I knew all the rules and tricks of the sport; what I didn’t know is that behind everything in baseball, even sayings, physics is involved.

The coach says, “This is the last inning, we have the momentum.” The announcer says, "The game is almost over and the Angels have the momentum.” The team captain says, “We have the momentum, we need to use it to finish them off!” These were some of the phrases I heard while I played baseball. Momentum can be defined as mass in motion. Since all objects have mass; if they are motion, then it has momentum. The amount of momentum that an object has depends on the mass and velocity. In baseball, mass can be compared to how many runs the team is ahead or behind and the velocity can be compared to the motivation the team has. When people use the word momentum in baseball they mean that the team is on the move and it’s going to take some effort to stop them.

While growing up, I remember hearing the coach say that the speed of the ball depended on how you grabbed the baseball and how fast you did the throwing movement. To be honest, I always thought that it wasn’t true and I wouldn’t really listen. I played catcher; all I worried about was telling the pitcher what to pitch.  I didn’t really think of the mechanisms that the pitcher used to throw a 90 mph fastball or a curve ball. Now that I am taking physics, it turns out that the coach was absolutely right. How a baseball travels through the air is due to aerodynamics. As the ball travels along the field, turbulence occurs in the stitches of the baseball allowing air to stick to them and cause them to slow down at a slower rate. The same stitches that help the baseball reduce its speed can also make the ball change directions drastically, also known as the curve ball. Baseball players use physics in order to make the ball go faster or throw a curve to strike out an opponent. 

When batting, baseball players want to hit the baseball with a part of the bat called the “sweet spot”. The reason why the baseball tends to go farther when hit in the sweet spot is not a mystery or miracle, it is simple physics. Objects vibrate at their natural frequency when they are disturbed. When waves interfere witch each other they form standing waves. These standing waves have alternating nodes and antinodes. The nodes are the regions where there is little to no amplitude, so there isn’t vibration. Baseball players want to hit the ball on the node of the bat, also known as the “sweet spot”, so there is little vibration and maximum energy transmitted to the baseball, making it reach farther. 

Baseball is impacted so greatly by physics that about four physics topics could be covered and taught with one simple baseball game. Physics cannot only explain a baseball game; it could also explain every single sport that exists. As a matter of fact, physics does not only explain why things happen in sports, it actually explains how everything happens in the world. 

"Baseball Physics." Top End Sports n. pag. Web. 22 Apr 2011. .

Giancoli, Douglas C. Physics for Scientists & Engineers with Modern Physics. 4th ed. Vol. 1. Upper Saddle River, N.J: Prentice Hall, 2009. Print.

"Momentum." Top End Sports n. pag. Web. 22 Apr 2011. .

"Nodes and Anti-nodes." Physics Classroom n. pag. Web. 22 Apr 2011. .

Understanding My Second Shot at Life

Ibrahim Rivera

Many can consider a second chance at life a miracle according to religious beliefs or just plain old good luck. After one experiences the scare, people tend to ask how did the mishap occur, and one can easily explain the circumstances as one is most likely to remember the situation, but the key question of how one survived never gets answered. What about the physics behind the second chance at life? Well I’m one of the people who have been in this unique position and the following accounts are the physics behind my survival.

As a third grade student I weighed approximately 90 pounds, compared to the average weight of a third grade student of 60.7 pounds according to Healthy Kids New Mexico. As an overweight kid I lacked the agility of a healthy boy my age, and this was proven when an iron gate fell on me. I didn’t have the reflexes to react on time and escape the scene, and since “the motion of falling objects is the simplest and most common example of motion with changing velocity,” the iron-gate fell on me hard, striking me noticeably harder on my head and knees. According to Galileo, the steeper the incline, the more rapidly the ball would have gained speed, as velocity increases more gradually on gentle slopes, but the motion is otherwise the same as the motion of a falling object. Galileo’s experiment applies to my incident as the 350-pound gate being originally at a 90-degree angle tilted when its support broke and its gravitational force was applied on my body. 

But what helped me was the friction between the gate and the ground, which consisted of slippery dirt that allowed me to push the gate further away from me as it began to fall on me. For example “in a collision, slowing down the deceleration by even a few tenths of a second can create a drastic reduction in the force involved.” Force can be calculated by the equation mass times acceleration, which therefore “cutting the deceleration in half also cuts the force in half.” This was the explanation to how not all the gate’s force fell completely on my body. I was able to push the gate as it began tilting towards me more than a couple of feet away from me, while I had the chance to grab the top of the 7-foot gate. Once it fell on me part of the force was exerted on my hands and arms, so not all the force could be applied to my face. This human instinct of protecting the face also helped me survive the massive forces being exerted, once the gate took me down to the ground. 

To the person with little insight in physics, would immediately tell me that my cause for survival was my weight. But if one uses Galileo’s experiments, the conclusion would lead one into believing that all heavy streamlined objects take about the same time to hit the ground, so my 90 pounds compared to the average 60.7 pounds of an average boy my age is irrelative and can be neglected as of this conclusion. The factor of eliminating as much of the force exerted on one was my case for survival, and it can be successfully attributed to deceleration. 

References:

Grabianowski, Ed. "HowStuffWorks "Force of Impact"." Howstuffworks "Auto ". N.p., n.d. Web. 17 Apr. 2011. . 

New Mexico Department of Health. "New Mexico BMI Surveillance Report." BMI Surveillance. N.p., n.d. Web. 17 Apr. 2011. . 

"The Motion of Falling Objects." Virtual Institute of Applied Science. N.p., n.d. Web. 17 Apr. 2011. .

Whirlpools and physics

Manuel Ortiz Acosta

Whirlpools have been legends since the existence of human civilizations. They are well known for their power and capabilities of sinking ships and disappearing people and civilizations. Everyone fears them, for they will swallow you if you get to close. A whirlpool is a swirling body of water. This phenomenon is one of the powers that the sea possess, and so it can be destructive. 

Since early times in literature we see monsters coming out of whirlpools and swallowing entire ships and killing everyone. . In Greek mythology we can find Charybdis the daughter of Poseidon, who is just a whirlpool it appears in the poems of The Odyssey, Jason and The Argonauts, and Ovid's Metamorphoses. Is that really true? These phenomena might have  enough power to sink a ship and it’s more than enough to drown humans and other animals

This phenomena can happen for many reasons. One of this is when two currents come together, this ones are known as tidal whirlpools. They usually happen because of the force of gravity, if you do an experiment with two bottles tied together one empty and another one with water when you change the position and the one with water is up, it’ll form a whirlpool while it goes down, this is because the water is more dense than the air and the gravity force pulls it down and that is when the water starts to whirl around creating a circular motion as it goes down with centripetal acceleration.

That is what happens with the whirlpools at sea. When less dense water is over more dense water the pressure pulls the less dense water down and it start whirling around in circular motion. In the center the whirlpool has negative pressure and that’s why the center is empty. In beaches where the sea has mountains, is a more favorable condition for whirlpools to occur since when the current flows the less dense water will be automatically over the denser water and the force of pressure acts and the water starts to whirls.

The question is how we can survive a whirlpool if we can. Many persons claim to have done it. Some say they used more speed in their boats, others more weight. What pulls you to the center of the whirlpool is the centripetal force and centripetal force is directly proportional to mass and the square of velocity, and indirectly proportional to the radius(the distance to the center of the whirlpool).  This means that if you have more mass there will have to be more centripetal force to be able to pull you down to the center of the circle. That is why lighter objects go to the center of the whirlpool and heavier objects stay out. Also if you have higher speed you can also survive it, because of the same reason, the whirlpool will need more force to pull you to the center and obviously if the distance from the center is more,  there will be less force acting on the object and it’ll be easier to get out from the circular motion and survive. The whirlpool will be need more force to get the object out from the inertia state and move it. When the process of the water moving  is over, the whirlpools  disappears because there is no more force acting on it to keep it motion.

Reference

Underwater Universe. (2011). The History Channel website. Retrieved 4:42, April 15, 2011, from http://www.history.com/shows/underwater-universe/episodes/episode-guide.

Smith, William; Dictionary of Greek and Roman Biography and Mythology, London (1873). "Scylla" 1.

Giancoli, Douglas C. Physics for Scientists & Engineers with Modern Physics. 4th ed. Vol. 1. Upper Saddle River, N.J: Prentice Hall, 2009. Print.

Dr. Lu, Junquiang. Class Lecture. General Physics I. University of Puerto Rico, Mayagüez Campus. Spring 2011.